The present invention relates generally to storing data and more particularly to a new and improved method for storing data onto magnetic tapes. The invention is intended to be used primarily with tapes being made for backup purposes, but, as will hereinafter become apparent, is not necessarily limited to tapes being prepared for that purpose. Also, although the invention is intended to be used in storing onto tapes data which is obtained from disks, it is not exclusively limited to data obtained from that type of source.
The present invention enables more data to be stored on a magnetic tape than previously possible, and in many cases enables a particular piece of data to be located faster than had been achievable in the past.
As will also hereinafter become apparent, the present invention is not limited to use with any one particular type of tape drive.
The conventional way to store data from disks onto a tape for backup purposes is to write the individual records from one file onto the tape, one record at a time. The individual records making up a file, if a file has more than one record, are separated from one another either by blank spaces commonly referred to as inter-record gaps or by tape or file marks, the type of separation being used depending on the nature of the programmatic method involved. After one file is written onto the tape, another file is written onto it in the same manner, and so forth. Successive files are usually separated by a tape mark with the tape mark being between the pair of inter-record gaps.
The basic problem with this arrangement for storing data onto a tape is that a considerable portion of the tape is not actually utilized for the storage of data but rather is taken up by the file gaps, the file marks and the inter record gaps. In some types of tapes, such as the helical scan, the area on the tape not used for storing data can sometimes be even larger than the area that is actually used for storing data, when dealing with large numbers of small files.
Retrieving a particular file on a tape formatted in the conventional way as described above also has disadvantages. First, it is necessary to prepare a list having the name and file number of each file on the tape. The list is usually put on the tape itself as an additional file at the end of a tape, or on a disk as a file or on a separate paper printout. Once the list has been prepared it is relatively simple and quick to locate a particular file; however, preparing the listing itself is very time consuming project and in many instances is not made at the time that data is initially put on the tape, but rather at the time the tape is being used to restore some information.
Accordingly, it is an object of this invention to provide a new and improved method for storing data on a magnetic tape.
It is another object of this invention to provide a method for storing data on a magnetic tape which does not involve the use of the usual number of inter-record gaps or file marks.
It is a further object of this invention to provide a method for storing data on a magnetic tape which does not require the creation of a separate listing to identify all of the data on the tape.
It is still a further object of this invention to provide a method of storing data onto a magnetic tape from one or more magnetic disks.
It is yet still a further object of this invention to provide a method of storing data onto a magnetic tape magnetic for use as a backup tape.
It is another object of this invention to provide a method of storing data onto a magnetic tape wherein the data is not formatted in terms of files and records.
It is still another object of this invention to provide a method of storing data onto a magnetic tape to provide a new and improved method for restoring all or a portion of the data stored on a magnetic tape in the manner as noted hereinabove.
It is yet still another object of this invention to provide a Multiple Input Source Organization (MISO) tape format for holding data from multiple input sources, simultaneously interspersed on the tape.